Study sites. Surveyed sectors on north and north-eastern Brazilian coast: 1 Marajó Bay 2 Eastern Pará state and 3 Maranhão and Piauí coastlines encompass part of Parnaíba Delta. Black dots representing stranding locations. Physeter macrocephalus (Pma), Balaenoptera brydei (Bbr), Balaenoptera physalus (Bph), Megaptera novaeangliae (Mno), Steno bredanensis (Sbr), Balaenoptera borealis (Bbo), Tursiops truncatus (Ttr), Globicephala macrorhynchus (Gma), Pseudorca crassidens (Pcr), Sotalia guianensis (Sgu), Peponocephala electra (Pel), Stenella attenuata (Sat), Lagenodelphis hosei (Lho), Delphinus sp. (Dsp) and Grampus griseus (Ggr).